WD phono/PSU III clone

[Graeme]

Hi all. This forum was recomended to me so ill document my build here

Ive built and modded my WD kit amp but am now trying my hand at building a clone.

This is the begining of a steep learning curve for me. It feeld like im diving in at the deep end but i think ive got my head round it all.

Heres what im up to. The following is 'copy and pasted' from my thread on another forum.

[Graeme]

Well, ive just been screwed for £800 wages so buying phono/psu III is now out the window

So, time to do some more learning (modding my kel84 has helped) and try and build a clone.

Ive studied the circuits and thought it through. I think i know what im doing but i guess we'll find out.

Im going to try to not pester everyone with questions and will update my progress as i go. It may be slow as i have no money to buy parts.

Should be fun!

Im going to write my component lists here too and mark them off as i source them, that way i can keep all my info in one place.
* = got
PSU III

caps
C1 100uf 450v
c2 100uf 450v
c5 100uf 63v*
c6 4700uf 16v*
c7 100uf 16v*

resistors
R1 100r 3w
R2 150k 2w
R3 22k 2w*
R4 1k 2w*
R5 100r 3w
R6 15k 2w*


Other
Tx*?
IEC socket
choke 15h 20mA
Voltage regulater U178S05 or LM1084
d1/2/3/4*
d5/6 ?
BR1 (same as BR1 in kel84?)*



Phono III
caps
c10/11 0.1uf 250v*
c12/13 10uf 450v
c14/15 8.2nf 1%
c16/17 220pf 1%*
c18/19 2.2uf 250v*
c20 100uf 450v

Resistors
r13/14 47k*
r15/16 1k*
r17/18 1.2k*
r19/20 100k*
r21/22 1m*
r23/24 316k 1%
r25/26 39.2k 1%*
r27/28 2.2k*
r29/30 330k
r31/32 180k 1%
r33/34 150k*
r35/36 1k*
r37/38 1m*
r41 1k 3w*

Other
phono sockets*
3 ecc83 (got 2 mullard)
3 valve base*

[Graeme]

So, i went through all the scrap i have and sourced a pityfull amount of stuff. At least its a start though.

I fitted leads to the socket tags so i can mount them and still get to the connections.
Not a big start but from little acorns

Not sure if im aproaching this the right way, but im basically just going to reproduce the diagrams in 3d form.



As i say, ill try not to pester and ask loads of questions but there may be the odd one or two as i go.
Im just going with gut instinct and no knowledge on how to actually construct this, plan is to just glue components down and hard wire, like a crossover.

If you notice me doing anything completely stupid, something that wont actually work, please let me know

Thanks, hope the thread is fun, and hopefully of benefit to other novices out there.

[Graeme]

Seems i cant post the pics yet, ill put them up in a few days.

[Nick]

The 2.5% 220pf cap will be good enough for now, get it working first. One thing you could consider is to ge a bunch of 220pf caps of 10% or so, and then if you want to put them in the post to me (Halifax) I can run them through the LCR meter and find the best matched pair. You could get even more involved and use Spice (or get someone else to do it) and see what small tweeks to the other 1% resistors you need to match what the caps values actually are.

[Graeme]

Right, this is where i show up my nievety.

LCR meter?
Spice?

My multimeter will test small value caps but it doesnt seem to be very reliable!

Im having to build this with whatever i can cobble together. If by some miracle it works at the end then ill think about re-building it better.

As i say, im on a super tight budget right now and as i only give myself a 50/50 chance of getting this working im reluctant to spend much money on it. Its as much of a learning exercise as anything else.

Ill use the 2.5% caps for now.
As for 1% resistors, i assume it doesnt actually matter what % rating the resistor has, as long as the resistor is within 1% of the stated value?

The only other things that i dont know about yet are...

The voltage regulator, i cant find one with the U1 78S05 number i (apparantly) need.
The Tx, i dont understand them yet so i guess ill have to buy that from WD
The diodes, whats needed arent listed on the schematic.
The bridge rectifer, again, type isnt mentioned.

Ive got the bridge rectifier i removed from my KEL84, anyone know if its the same one? Would be a stroke of luck if it is

Ill keep chipping away at the build as and when i can afford some components. I dont care if it takes me a year to build, although it would be nice if it didnt!

[Nick]

LCR meter:

Inductance (L), Capacitance (C), Resistance (R)

Spice:

Software that simulates the operation of electronics circuit, there are threads on the forum about it. Its very usefull for phono stages, allowing the effect of component values on the RIAA equilisation to be quickly checked.

[Graeme]

Ah, interesting.

Ill go read up about spice.

Thanks.

[Graeme]

Just a quick question, ecc83, pins 4 and 5 are both heaters and will be joined together, pin 9 is hot.

I assume hot is heater + and H is heater- ?

A also assume that it doesnt really matter anyway?

[Nick]

4,5 and 9 are the heater connections simple as that, there are no hot, cold, +ve or -ve connections. for 12v heaters connect across 4 and 5 and leave 9 unused, for 6v heaters connect 4 and 5 together and voltage between 4+5 and 9

[Graeme]

Thought so, thanks.

[Dave the bass]

My multimeter will test small value caps but it doesnt seem to be very reliable!

Hi ya Graeme,

I don't know if you're aware but when using the cap function on a Multimeter its VERY important to not hold the legs of the components or the meter leads. Our little fingers look like capacitance to a MM and will often attempt to read 'us' in addition to the capacitor!

Just summat to bear in mind.

DTB

[Toppsy]

...................will often attempt to read 'us' in addition to the capacitor!

OK out of curiosity then what reading does it give for DTB little digits?

[Graeme]

My multimeter will test small value caps but it doesnt seem to be very reliable!

Hi ya Graeme,

I don't know if you're aware but when using the cap function on a Multimeter its VERY important to not hold the legs of the components or the meter leads. Our little fingers look like capacitance to a MM and will often attempt to read 'us' in addition to the capacitor!

Just summat to bear in mind.

DTB

Thanks for the tip, ill try again later. It will only test up to 2uf anyway so its not massively usefull.

[Graeme]

On a seperate note, hot coffee with 3 sugars has quite alot of resistance